The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. The embodiments illustrated herein are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown, wherein:
The input module 120 may include an input translation circuit 126, a first power supply 128, and an electrical-to-optical (E/O) converter 130. The input translation circuit 126 is electrically connected to the external negative and positive terminals 122, 124 and is used to measure an electrical characteristic of the circuit 10. For example, the input translation circuit 126 may be a voltmeter, an ammeter, or an ohmmeter. No matter the particular electrical characteristic of the circuit 10 being measured, other electrical characteristics of the circuit 10 can be inferred using, for example, Ohm's law. In certain aspects of the signal probe 100, however, the input translation circuit 126 measures a differential voltage VI and converts the differential voltage VI into a first electrical signal having a current IIM.
The first power supply 128 drives the input translation circuit 126, and the first power supply 128 is not limited as to a particular type of power supply. For example, the first power supply 128 may be a parasitic power supply. However, in certain aspects of the signal probe 100, the first power supply 128 is an isolated DC power supply.
The E/O converter 130 converts the first electrical signal from the input translation circuit 126 into a light signal, which is then input into the fiber optic line 160. Many types of E/O converters 130 are known, and the signal probe 100 is not limited as to a particular type of E/O converter 130. Examples of acceptable E/O converters 130 include a light-emitting diode (LED) and a laser diode.
These types of E/O converters 130, however, have differing characteristics. For example, the output of an LED is linearly proportional to the drive current, whereas the output of a laser diode is proportional to current above a threshold current, which typically between about 5 to about 40 mA. Also, other differences include that a LED has a wider spectral width than a laser diode, whereas the output optical beam divergence is higher with a LED and lower with a laser diode.
The fiber optic line 160 is essentially immune to electromagnetic noise. As a result, the light signals being sent from the input module 120 to the output module 140 are not affected by the extreme electromagnetic environment created by the strong EMF event 20 while the circuit 10 is under test.
The output module 140 may include an optical-to-electrical (O/E) converter 144, an output translation circuit 146, and a second power supply 148. After passing through the fiber optic line 160, the optical signal is received by the O/E converter 144, which converts the optical signal into a second electrical signal. Many types of O/E converters 144 are known, and the signal probe 100 is not limited as to a particular type of E/O converter 144.
The output translation circuit 146 receives the second electrical signal from the O/E converter 144 and translates the second electrical signal into a desired output that is reflective of the electrical characteristic of the circuit 10 being measured. The desired output is then transmitted via the connector 150 to a standard measurement device, such as an electronic oscilloscope 160. The desired output is not limited as to a particular electric characteristic. Also, the transfer characteristics, VI to VO, of the signal probe 100 may be adjusted such that the signal VO measured on the scope 160 directly corresponds to the voltage VI being measured at the circuit 10.
The second power supply 148 drives the output translation circuit 146, and the second power supply 148 is not limited as to a particular type of power supply. For example, the second power supply 148 may be a parasitic power supply. However, in certain aspects of the signal probe 100, the second power supply 148 is an isolated DC power supply.
The signal being generated by the output module 140 may be controlled and/or modified, for example, using amplifier gain or scaling, signal synchronization, power control or through the use of other programmable parameters. This control or modification of the signal may take place within the output module 140 or after the signal is outputted via the output connector 150 using, for example, the scope 160 or any other device so capable.